Hello,
I am designing a small, simple 12V motor controller fed by a L298 H-bridge driver. The H-bridge input pins are supplied by means of PWM at 40 Hz. The motor can be connected or disconnected from the output even with the input and enable on. For this reason, I am interested in adding additional circuitry in order to obtain a binary signal of consumption using the current sensor pins; that is obtain a permanent high level while some current is detected and a permanent low level when no current is detected (after at least 1 period, but this is flexible).
The idea is to use a 0.5 ohm resistor to connect the sense pin to ground, and then use the voltage across the resistor to obtain the signal. I consider that the voltage measured will be from 5 mV to 1V and the Duty Cycle can be down to 1%. Because the sensor signal is also pulsed, I need somehow to filter it and obtain an stable output while consumption is 'on'. The problem is that I had not success to set properly a low-pass filter plus op-amp buffer configuration from this signal working reliably with all the mentioned conditions. I also tried to pre-amplify the sensor signal with another op-amp, then output that into the low-pass filter plus buffer, but had no success too.
Any idea is appreciated. Thank you very much!
